crate_universe: Don't include crate name in build script path. (#2663)

This PR shortens the path to the build script (potentially
significantly), which helps with long-path issues on Windows.
This change is motivated by the crate `tree-sitter-embedded-template`,
which has a too long path to the compiled build script otherwise, and
which then fails to build on Windows in a `bzlmod` setting.
Fixes #2520.

The cargo build script name was used to automatically derive the cargo
package name, this now went into a separate override parameter that is
generated by the crate-universe tooling.
There's never two build scripts in a single crate, so I don't see how
having a single build script target with a single name would be a
problem.

cargo/private/cargo_build_script.bzl

@@ -151,7 +151,9 @@ def _cargo_build_script_impl(ctx):
         stderr = ctx.actions.declare_file(ctx.label.name + ".stderr.log"),
     )
 
-    pkg_name = name_to_pkg_name(ctx.label.name)
+    pkg_name = ctx.attr.pkg_name
+    if pkg_name == "":
+        pkg_name = name_to_pkg_name(ctx.label.name)
 
     toolchain_tools = [toolchain.all_files]
 
@@ -373,6 +375,9 @@ cargo_build_script = rule(
         "links": attr.string(
             doc = "The name of the native library this crate links against.",
         ),
+        "pkg_name": attr.string(
+            doc = "The name of package being compiled, if not derived from `name`.",
+        ),
         "rundir": attr.string(
             default = "",
             doc = dedent("""\
@@ -388,7 +393,7 @@ cargo_build_script = rule(
                 List of compiler flags passed to `rustc`.
 
                 These strings are subject to Make variable expansion for predefined
-                source/output path variables like `$location`, `$execpath`, and 
+                source/output path variables like `$location`, `$execpath`, and
                 `$rootpath`. This expansion is useful if you wish to pass a generated
                 file of arguments to rustc: `@$(location //package:target)`.
             """),

cargo/private/cargo_build_script_wrapper.bzl

@@ -31,6 +31,7 @@ def cargo_build_script(
         visibility = None,
         tags = None,
         aliases = None,
+        pkg_name = None,
         **kwargs):
     """Compile and execute a rust build script to generate build attributes
 
@@ -92,14 +93,15 @@ def cargo_build_script(
 
     Args:
         name (str): The name for the underlying rule. This should be the name of the package
-            being compiled, optionally with a suffix of `_build_script`.
+            being compiled, optionally with a suffix of `_bs`. Otherwise, you can set the package name via `pkg_name`.
         edition (str): The rust edition to use for the internal binary crate.
         crate_name (str): Crate name to use for build script.
         crate_root (label): The file that will be passed to rustc to be used for building this crate.
         srcs (list of label): Souce files of the crate to build. Passing source files here can be used to trigger rebuilds when changes are made.
         crate_features (list, optional): A list of features to enable for the build script.
         version (str, optional): The semantic version (semver) of the crate.
         deps (list, optional): The build-dependencies of the crate.
+        pkg_name (string, optional): Override the package name used for the build script. This is useful if the build target name gets too long otherwise.
         link_deps (list, optional): The subset of the (normal) dependencies of the crate that have the
             links attribute and therefore provide environment variables to this build script.
         proc_macro_deps (list of label, optional): List of rust_proc_macro targets used to build the script.
@@ -131,9 +133,12 @@ def cargo_build_script(
     # available both when we invoke rustc (this code) and when we run the compiled build
     # script (_cargo_build_script_impl). https://github.com/bazelbuild/rules_rust/issues/661
     # will hopefully remove this duplication.
+    if pkg_name == None:
+        pkg_name = name_to_pkg_name(name)
+
     rustc_env = dict(rustc_env)
     if "CARGO_PKG_NAME" not in rustc_env:
-        rustc_env["CARGO_PKG_NAME"] = name_to_pkg_name(name)
+        rustc_env["CARGO_PKG_NAME"] = pkg_name
     if "CARGO_CRATE_NAME" not in rustc_env:
         rustc_env["CARGO_CRATE_NAME"] = name_to_crate_name(name_to_pkg_name(name))
 
@@ -173,5 +178,6 @@ def cargo_build_script(
         rustc_flags = rustc_flags,
         visibility = visibility,
         tags = tags,
+        pkg_name = pkg_name,
         **kwargs
     )

crate_universe/src/rendering.rs

@@ -380,7 +380,7 @@ impl Renderer {
                     starlark.push(Starlark::Alias(Alias {
                         rule: AliasRule::default().rule(),
                         name: target.crate_name.clone(),
-                        actual: Label::from_str(&format!(":{}_bs", krate.name)).unwrap(),
+                        actual: Label::from_str("_bs").unwrap(),
                         tags: BTreeSet::from(["manual".to_owned()]),
                     }));
                 }
@@ -435,8 +435,8 @@ impl Renderer {
             //
             // Do not change this name to "cargo_build_script".
             //
-            // This is set to a short suffix to avoid long path name issues on windows.
-            name: format!("{}_bs", krate.name),
+            // This is set to a short name to avoid long path name issues on windows.
+            name: "_bs".to_string(),
             aliases: SelectDict::new(self.make_aliases(krate, true, false), platforms),
             build_script_env: SelectDict::new(
                 attrs
@@ -484,6 +484,7 @@ impl Renderer {
             edition: krate.common_attrs.edition.clone(),
             linker_script: krate.common_attrs.linker_script.clone(),
             links: attrs.and_then(|attrs| attrs.links.clone()),
+            pkg_name: Some(krate.name.clone()),
             proc_macro_deps: SelectSet::new(
                 self.make_deps(
                     attrs
@@ -1058,7 +1059,7 @@ mod test {
         assert!(build_file_content.contains("\"crate-name=mock_crate\""));
 
         // Ensure `cargo_build_script` requirements are met
-        assert!(build_file_content.contains("name = \"mock_crate_bs\""));
+        assert!(build_file_content.contains("name = \"_bs\""));
     }
 
     #[test]

crate_universe/src/utils/starlark.rs

@@ -114,6 +114,8 @@ pub(crate) struct CargoBuildScript {
     pub(crate) linker_script: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub(crate) links: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub(crate) pkg_name: Option<String>,
     #[serde(skip_serializing_if = "SelectSet::is_empty")]
     pub(crate) proc_macro_deps: SelectSet<Label>,
     #[serde(skip_serializing_if = "SelectScalar::is_empty")]

docs/cargo.md

@@ -65,7 +65,8 @@ A rule for generating variables for dependent `cargo_build_script`s without a bu
 <pre>
 cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-edition">edition</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_root">crate_root</a>, <a href="#cargo_build_script-srcs">srcs</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>,
                    <a href="#cargo_build_script-link_deps">link_deps</a>, <a href="#cargo_build_script-proc_macro_deps">proc_macro_deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-data">data</a>, <a href="#cargo_build_script-compile_data">compile_data</a>, <a href="#cargo_build_script-tools">tools</a>, <a href="#cargo_build_script-links">links</a>,
-                   <a href="#cargo_build_script-rundir">rundir</a>, <a href="#cargo_build_script-rustc_env">rustc_env</a>, <a href="#cargo_build_script-rustc_env_files">rustc_env_files</a>, <a href="#cargo_build_script-rustc_flags">rustc_flags</a>, <a href="#cargo_build_script-visibility">visibility</a>, <a href="#cargo_build_script-tags">tags</a>, <a href="#cargo_build_script-aliases">aliases</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
+                   <a href="#cargo_build_script-rundir">rundir</a>, <a href="#cargo_build_script-rustc_env">rustc_env</a>, <a href="#cargo_build_script-rustc_env_files">rustc_env_files</a>, <a href="#cargo_build_script-rustc_flags">rustc_flags</a>, <a href="#cargo_build_script-visibility">visibility</a>, <a href="#cargo_build_script-tags">tags</a>, <a href="#cargo_build_script-aliases">aliases</a>,
+                   <a href="#cargo_build_script-pkg_name">pkg_name</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
 </pre>
 
 Compile and execute a rust build script to generate build attributes
@@ -131,7 +132,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 
 | Name  | Description | Default Value |
 | :------------- | :------------- | :------------- |
-| <a id="cargo_build_script-name"></a>name |  The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of <code>_build_script</code>.   |  none |
+| <a id="cargo_build_script-name"></a>name |  The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of <code>_bs</code>. Otherwise, you can set the package name via <code>pkg_name</code>.   |  none |
 | <a id="cargo_build_script-edition"></a>edition |  The rust edition to use for the internal binary crate.   |  `None` |
 | <a id="cargo_build_script-crate_name"></a>crate_name |  Crate name to use for build script.   |  `None` |
 | <a id="cargo_build_script-crate_root"></a>crate_root |  The file that will be passed to rustc to be used for building this crate.   |  `None` |
@@ -153,6 +154,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 | <a id="cargo_build_script-visibility"></a>visibility |  Visibility to apply to the generated build script output.   |  `None` |
 | <a id="cargo_build_script-tags"></a>tags |  (list of str, optional): Tags to apply to the generated build script output.   |  `None` |
 | <a id="cargo_build_script-aliases"></a>aliases |  Remap crates to a new name or moniker for linkage to this target.             These are other <code>rust_library</code> targets and will be presented as the new name given.   |  `None` |
+| <a id="cargo_build_script-pkg_name"></a>pkg_name |  Override the package name used for the build script. This is useful if the build target name gets too long otherwise.   |  `None` |
 | <a id="cargo_build_script-kwargs"></a>kwargs |  Forwards to the underlying <code>rust_binary</code> rule. An exception is the <code>compatible_with</code> attribute, which shouldn't be forwarded to the <code>rust_binary</code>, as the <code>rust_binary</code> is only built and used in <code>exec</code> mode. We propagate the <code>compatible_with</code> attribute to the <code>_build_scirpt_run</code> target.   |  none |
 
 

docs/flatten.md

@@ -1571,7 +1571,8 @@ A collection of files either found within the `rust-stdlib` artifact or generate
 <pre>
 cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-edition">edition</a>, <a href="#cargo_build_script-crate_name">crate_name</a>, <a href="#cargo_build_script-crate_root">crate_root</a>, <a href="#cargo_build_script-srcs">srcs</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>,
                    <a href="#cargo_build_script-link_deps">link_deps</a>, <a href="#cargo_build_script-proc_macro_deps">proc_macro_deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-data">data</a>, <a href="#cargo_build_script-compile_data">compile_data</a>, <a href="#cargo_build_script-tools">tools</a>, <a href="#cargo_build_script-links">links</a>,
-                   <a href="#cargo_build_script-rundir">rundir</a>, <a href="#cargo_build_script-rustc_env">rustc_env</a>, <a href="#cargo_build_script-rustc_env_files">rustc_env_files</a>, <a href="#cargo_build_script-rustc_flags">rustc_flags</a>, <a href="#cargo_build_script-visibility">visibility</a>, <a href="#cargo_build_script-tags">tags</a>, <a href="#cargo_build_script-aliases">aliases</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
+                   <a href="#cargo_build_script-rundir">rundir</a>, <a href="#cargo_build_script-rustc_env">rustc_env</a>, <a href="#cargo_build_script-rustc_env_files">rustc_env_files</a>, <a href="#cargo_build_script-rustc_flags">rustc_flags</a>, <a href="#cargo_build_script-visibility">visibility</a>, <a href="#cargo_build_script-tags">tags</a>, <a href="#cargo_build_script-aliases">aliases</a>,
+                   <a href="#cargo_build_script-pkg_name">pkg_name</a>, <a href="#cargo_build_script-kwargs">kwargs</a>)
 </pre>
 
 Compile and execute a rust build script to generate build attributes
@@ -1637,7 +1638,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 
 | Name  | Description | Default Value |
 | :------------- | :------------- | :------------- |
-| <a id="cargo_build_script-name"></a>name |  The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of <code>_build_script</code>.   |  none |
+| <a id="cargo_build_script-name"></a>name |  The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of <code>_bs</code>. Otherwise, you can set the package name via <code>pkg_name</code>.   |  none |
 | <a id="cargo_build_script-edition"></a>edition |  The rust edition to use for the internal binary crate.   |  `None` |
 | <a id="cargo_build_script-crate_name"></a>crate_name |  Crate name to use for build script.   |  `None` |
 | <a id="cargo_build_script-crate_root"></a>crate_root |  The file that will be passed to rustc to be used for building this crate.   |  `None` |
@@ -1659,6 +1660,7 @@ The `hello_lib` target will be build with the flags and the environment variable
 | <a id="cargo_build_script-visibility"></a>visibility |  Visibility to apply to the generated build script output.   |  `None` |
 | <a id="cargo_build_script-tags"></a>tags |  (list of str, optional): Tags to apply to the generated build script output.   |  `None` |
 | <a id="cargo_build_script-aliases"></a>aliases |  Remap crates to a new name or moniker for linkage to this target.             These are other <code>rust_library</code> targets and will be presented as the new name given.   |  `None` |
+| <a id="cargo_build_script-pkg_name"></a>pkg_name |  Override the package name used for the build script. This is useful if the build target name gets too long otherwise.   |  `None` |
 | <a id="cargo_build_script-kwargs"></a>kwargs |  Forwards to the underlying <code>rust_binary</code> rule. An exception is the <code>compatible_with</code> attribute, which shouldn't be forwarded to the <code>rust_binary</code>, as the <code>rust_binary</code> is only built and used in <code>exec</code> mode. We propagate the <code>compatible_with</code> attribute to the <code>_build_scirpt_run</code> target.   |  none |